Drive means for mixing or blending apparatus



Oct

E. STELZER 3,061,751

DRIVE MEANS FOR MIXING OR BLENDING APPARATUS Filed July 7, 1959 Inventor sew/1v STEL 25/? United States Patent Ofilice 3,061,751 Patented Oct. 30, 1962 3,061,751 DRIVE MEANS FOR MEXING R BLENDING APPARATUS Erwin Stelzer, Landfurtweg 66, Warburg, Westphalia, Germany Filed July 7, 1959, Ser. No. 825,546 Claims priority, application Germany July 7, 1958 8 Claims. (Cl. 310-269) This invention relates to drive means for mixing, blending and like apparatus, and in particular refers to electric drive means for agitators.

There are known electric drive means of this kind for machines, which are mounted on the cover of the agitator vessel and include an electric motor and a gear reducer for driving the agitator shaft. When sensitive materials are to be handled in the apparatus, it becomes, however, imperative to prevent any traces of lubricant, oil or other foreign matter, such as dust particles, from entering the interior of the vessel.

When using a gear reducer at the upper end of the agitator shaft, it is almost impossible to avoid that 00- casionally small amounts of lubricant oil drip off. Since the apparatus cannot be watched constantly, it cannot be avoided that at least some foreign matter, or in particular lubricating oil, seeps or oozes out and mixes with the contents of the vessel.

For agitating sensitive substances, for example, foods,

the agitator shafthas to be rotated very slowly so that v mixing apparatus.

The present invention has therefore as one of its objects to provide means completely overcoming the aforesaid and other difiiculties.

:It is a further object of this invention to provide means contriving electric drive means for directly imparting movement to an agitator shaft or the like at very low speed without the intermediary of speed reducing means.

Another object of the invention is to provide means contributing to the disposition of an electric drive motor directly on top of the cover of the vessel or housing in which the agitator blades or paddles are rotated.

Furthermore, it is an object of this invention to provide vertical electrical drive means for agitators or the like, having main bearing means remote from the agitator shaft in order to prevent lubricants or like foreign matter from getting into the substances under treatment or to be agitated. I i I I A further object of the invention is to provide rigid mounting meansforan electric drive for preventing vibration during slow speed operation of the electric motor.

Another object of the invention is to provide means arranging the drive means for an agitator or like apparatus so that the agitator or blade shaft may be readily and easily manipulated for withdrawal from the interior of the vessel.

Still another object of this invention is to provide means affording a direct and compact drive for the agitator and like apparatus, whereby the number of operable parts is greatly reduced or simplified.

The invention consists in such novel features, arrangements and combinations of parts as may be shown and described in connection with the apparatus herein disclosed by way of example only and as illustrative of a preferred embodiment.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom or may be learned by practicing the invention, the

same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

In the accompanying drawing which forms part of this specification, one embodiment of the apparatus pursuant to the invention is illustrated merely by way of example.

in the following description and in the claims, parts will be identified by specific names for convenience, but such names are intended to be as generic in their application to similar parts as the art will permit. Like reference characters denote like parts in the drawing, which latter is a cross-section of the head of an agitator or paddle shaft and a slow speed electric motor, partly broken away, directly mounted on said shaft.

Referring now more particularly to the attached drawing there is disclosed a bushing 2 detachably mounted on the vertical hollow shaft 1 of an agitator by means of a concentric bushing 3 and a cone-shaped bushing 4 which fits over a correspondingly cone-shaped bushing 33 abutting against a protruding ring 34 of the shaft 1.

Shaft 1 has a threaded upper end 31. A nut 28 having a protecting and depending flange 26 engages the threaded end 31 and provides for a solid connection between shaft 1 and bushing 2 and retains bushing 3 in position. A cover nut or cap 29 serves as a locknut and as a seal for the uppermost end of hollow shaft 1. A bushing 32 is pressed into the upper end 31 of the hollow shaft, against an inner shoulder thereof, a notch 32a being provided in bushing 32 for holding the shaft 1 during the assembly of the drive parts. A set screw 5 is arranged to extend through the cone-shaped bushing assembly 4, 33 for securing the aforesaid drive parts in assembled relation to shaft 1 so that shaft 1 and all parts thereon are returned to their dynamically balanced condition, whenever the shaft has been taken off or was removed for any reason of repair or the like.

Bushing 2 has an enlargement or central flange portion 6 and a threaded upper end 7 and a threaded lower end 8. In the center flange portion 6 there is located a key 13 which engages a keyway 12 in the hub 11 of the rotor generally designated 35 of the electric motor. An upper nut 9 and a lower nut 10 secure hub 11 to the bushing 2 in axial direction.

The rotor 35 is composed of a ring-shaped supporting plate 14, welded to bushing 11 and stiffened by a plurality of triangular reinforcing plates 15. Assembled with plate 14, by means of a lower ring-shaped counterplate 25 and by a plurality of bolts 16', is the outer race 24 of a ball bearing 23. Rotor plates 17 are secured in their proper place on the periphery of rotor 35 by the same bolts 16.

The inner race 22 of the ball bearing 23 is mounted inside the inner flange 20 of a U-shaped channel section composed of outer flange 21 and inner flange 20 welded to ring-shaped bottom plate 19. Inside the outer flange 21 and arranged opposite the rotor plates 17 are fastened a corresponding number of core plates 27, constituting the stator 36 of the electric motor.

In order to obtain a very low number of revolutions per minute of the rotor, e.g., approximately revolu tions per minute-under normal A.C. poly-phase frequencies and voltages, the electric motor composed of rotor 35 and stator 36 possesses, besides a large number of poles on account of its large diameter and reduced axial length, so-called fractional windings, in which the number of slots per pole and phase is not an integer.

However, such windings generate strong unsymmetrical forces which result in a rotating power vector. This rotating mechanical force is very great so that the ringshaped bottom plate 19 has a plurality of threaded holes 18 for safely securing structure 19-20-21 to the cover of the agitator vessel or the like (cover and agitator vesselIbein-g omitted for the sake of clarity), preventing any vibrations of the .drive.

While the invention has been described and illustrated with respect to a certain particular preferred example which gives satisfactory results, it will be understood by those skilled in the art after understanding the principle of the invention, that various other changes and modifications may be made without departing from the spirit and scope of the invention and it is intended therefore in the appended claims to cover all such changes and modifications.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. A polyphase electric motor for directly driving an agitator at a very low angular velocity, said motor comprising, in combination, an annular stator support having a channel cross-section including an annular base and a pair of substantially cylindrical radially spaced coaxial inner and outer flanges, of substantially equal axial extent, normal to the respective inner and outer peripheries of the base and extending in the same axial direction from the latter; an annular stator mounted on the inner surface of said outer flange; a rotor operatively associated with said stator and including a substantially flat annular plate extending at least partially over the open side of said stator support coaxially with said stator and having an inner diameter not exceeding the inner diameter of said inner flange, and constructed and arranged for securement of its inner periphery to an agitator drive shaft, and rotor elements secured to said annular plate adjacent the outer periphery thereof and disposed within said channel cross-section in radially spaced relation to said annular stator; and an anti-friction bearing for rotatably supporting said rotor on said stator support and including an outer raceway secured to said annular plate, an inner raceway secured to the outer surface of said inner flange, and anti-friction elements movable in said raceways.

2. A polyphase electric motor, as claimed in claim 1, in which said rotor elements comprise rotor plates; and means conjointly securing said rotor plates and said outer raceway to said substantially flat annular plate.

3. A polyphase electric motor, as claimed in claim 1, including an agitator drive shaft; a bushing on said drive shaft; and means detachably securing said bushing on said drive shaft; the inner periphery of said substantially fiat annular plate being fixedly connected with said bushing for conjoint rotation therewith.

4. A polyphase electric motor, as claimed in claim 3, including a hub rigidly connected to the inner periphery .of said substantially fiat annular plate and embracing said bushing; and means securing said hub against angular and axial movement relative to said bushing.

5. A polyphase electric motor, comprising, in combination, an annular stator support having a channel cross section including an annular base and a pair of substantially cylindrical radially spaced coxial inner and outer flanges, of substantially equal axial extent, normal to the respective inner and outer peripheries of the base and extending in the same axial direction therefrom; an annular stator mounted on the inner surface of said outer flange intermediate the axial extent thereof; a rotor shaft coaxial with said stator support; the inner surface of said inner flange being spaced substantially radially from said shaft; a rotor secured to said shaft and extending over the open side of said channel cross-section, said rotor including pole face means extending within said channel cross-section and spaced radially from the inner surface of said stator to form an air gap therewith; and an antifriction bearing for rotatably supporting said rotor on said stator support and including an outer raceway secured to said rotor radially inwardly of said pole faced forming means and within said channel cross-section, an inner raceway secured to the outer surface of said inner flange, and anti-friction elements movable in said raceways. i

6-. An electric motor as claimed in claim 5, in which said rotor includes a substantially flat annular plate extending over the open end of said channel cross-section and supporting said pole face forming means and said outer raceway; the outer diameter of said substantially flat annular plate being less than the outer diameter of said rotor support and greater than the inner diameter thereof; the inner diameter of said substantially fiat annular plate being substantially .less than the inner diameter of said inner flange; the inner periphery of said substantially flat annular plate being drivingly connected to said shaft; whereby the inner surface of said inner flange is spaced a substantial radial distance from said shaft.

7. An electric motor as claimed in .claim 6, in which said rotor includes a second substantially flat annular plate spaced axially from said first mentioned substantially flat annular plate and having an outer diameter equal to that of the latter and an inner diameter somewhat in excess of the outer diameter of said inner flange; said pole face forming means and said anti-friction hearing being disposed axially between said first and secondmentioned substantially flat annular plates; and means securing said second-mentioned substantially flat annular plate to said first-mentioned substantially flat annular plate to maintain said pole faced forming means and said outer raceway fixed to said first-mentioned substantially fiat annular plate.

8. An electric motor as claimed in claim 5, said rotor including a hub keyed to said shaft; and removable bushings mounted on said shaft and cooperable with said hub to fix the latter against axial movement relative to said shaft.

References Cited in the file of this patent UNITED STATES PATENTS 1,147,038 Mueller July 20, 1915 1,422,414 Burke July 11, 1922 1,808,572 Reist June 2, 1931 2,475,776 Brainard July 12, 1949 2,505,770 Hill May 2, 1950 2,691,124 Aske Oct. 5, 1954 2,857,534 Beach Oct. 21, 1958 

